German patent 31 49 067 discloses a frictional revolving joint of the aforementioned type for a sleeve on a shaft.
The ring-shaped pressure chamber referred to as the pressure chamber is bounded on the side directed towards the shaft by the tapered ring arrangement and on the side directed out-wards from the shaft by a ring-shaped called a ring-shaped shoulder. The tapered ring arrangement comprises two tapered ring sections referred to as pressure rings and a sleeve. In the known frictional revolving joint, the ring-shaped element and a clamping ring element called the outer ring form a one-piece part and its outer end forming the ring-shaped element surrounds the ring-shaped pressure chamber end directed away from the shaft.
The tapered ring sections are screwed together and in the aforementioned manner together form the tapered ring.
The outer end of one clamping ring element engaging over the ring-shaped pressure chamber is displaceably mounted on the circumferential surface of the other clamping ring element. For sealing the ring-shaped pressure chamber, between the circumferential surface of one clamping ring element and the inner surface of the other clamping ring element engaging over the ring-shaped pressure chamber is provided a sealing ring.
The two clamping ring elements form the clamping ring surrounding the tapered ring sections.
The ring-shaped pressure chamber can be directly supplied with hydraulic fluid by means of a hydraulic connection and at least one duct.
For sealing the ring-shaped pressure chamber with respect to a sleeve or shaft, a sealing ring is provided at the junction point of the two tapered ring sections.
The known coupling functions as follows. By means of the hydraulic connection and the duct fluid-connected thereto, the ring-shaped pressure chamber is supplied with hydraulic fluid. As a result of the hydraulic fluid, the two clamping ring elements move simultaneously against the rising conical outer surfaces of the tapered ring sections. The consequence of this is that the tapered ring sections are pressed against the sleeve and the latter is in turn pressed against the shaft. Thus, a frictional connection is formed between the shaft and the sleeve. There is also a mechanical securing of the braced position.
As a result of the provision of sealing rings, the ring-shaped pressure chamber is not hermetically sealed. Hydraulic fluid penetrates between the conical outer surfaces of the tapered ring sections and the conical inner surfaces of the clamping ring elements. As a result, in the case of high operating pressures, larger hydraulic fluid quantities migrate along the conical outer surfaces of the tapered ring sections and can therefore escape outwards.
It is disadvantageous that the pressure in the ring-shaped pressure chamber necessary for the clamping of the tapered ring sections cannot be increased over and beyond a certain amount, because in the case of particularly high operating pressures hydraulic fluid escapes outwards to a greater extent and consequently limits the pressure.
In addition, the known frictional revolving joints are expensive as regards maintenance, because firstly the hydraulic fluid in the pressure system must be constantly monitored and optionally topped up and secondly it must be ensured that the surfaces between the inside of the sleeve or between the insides of the tapered ring sections and the outside of the shaft remain free from hydraulic fluid, so that it is ensured that there is a frictional grip between the shaft and the sleeve or the inside of the tapered ring sections in operation.
The problem therefore exists of so further developing a frictional revolving joint of the aforementioned type that, whilst avoiding the indicated disadvantages of the prior art for each application, there is a reliable clamping of the revolving joint to the shaft even in the case of high operating pressures in the ring-shaped pressure chamber. It is also preferable to avoid hydraulic fluid passing outside the frictional revolving joint and particularly into the space between the shaft and the inner surface of the tapered ring arrangement.